Sensibly equivalent¶ to:
The EM4 is a dual sensitivity magic eye tuning indicator, electrically identical to the EM34 (IO base). Mullard describe this device as suited to both receiver tuning indication and test equipment null indications. The grid voltage change is 0 - 5 volts and 0 - 16 volts. The display is viewed end on.
The Ct8 base was not a successful method of achieving long term low resistance contacts.
This valve has to be one of the most beautiful products of the technology and is a delight to behold.
The wide glass envelope is 25 mm in diameter and, excluding the Ct8 base contacts is 73 mm tall.
References: Data-sheet & 1043. Type EM4 was first introduced in 1939.
Absolute Maximum Operating Conditions¶
PDF scanned from an original document held by the museum
Updated February 02, 2013. shape:wide.glass.tube construction:pinch type:tuning.indicator age:1930.1940 base:ct8 heater:6.3v pins:8 pin:1.- pin:2.h pin:3.h pin:4.k pin:5.a.a(d1) pin:6.g1 pin:7.t pin:8.a.a(d1)